Tetravalent vanadium compounds which are soluble in organic solvents

ABSTRACT

A compound of tetravalent vanadium of the general formula ##STR1## wherein M represents a metal of the fourth group of the Periodic Table of the Elements and R represents and alkyl, cycloalkyl or aryl moiety of 1 to 20 carbon atoms and a process for its preparation. Also disclosed is the use of such vanadium compound as a catalyst for homopolymerization, copolymerization or terpolymerization of various monomers including olefins and vinyl monomers.

This is a division of application Ser. No. 179,586, filed Aug. 21, 1980,now U.S. Pat. No. 4,324,736, Apr. 13, 1982.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to new vanadium (IV) alcoholates which aresoluble in organic solvents and have greater stability than knownvanadium alcoholates.

2. Discussion of Prior Art

Alcoholates of tetravalent vanadium, which are used, for examples, aspolymerization catalysts, are already known. They correspond to theformula V(OR)₄ and they are soluble in some polar organic solvents.However, they are expensive and difficult to prepare, because theycannot be made by the direct reaction of VCl₄ with alcohols, because ofthe proneness of this compound to hydrolysis. Instead, VCl₄ has to bereacted with lithium dialkylamide and the tetrakis-(dialkylamino)vanadium (IV) thus obtained must be subjected to alcoholysis.

These known alcoholates of tetravalent vanadium also have thedisadvantage that they are not thermostable. At temperatures above 100°C., they begin to decompose. Their shelf life also leaves much to bedesired, and they can be stored satisfactorily only if certainprecautionary rules are followed. Also the alcoholates of pentavalentvanadium, such as for example VO(OCH₃)₃ or VO(OC₂ H₅)₃, which are alsoused as catalysts, have the same instability, so that they are notsatisfactory replacements for the vanadium (IV) compounds.

SUMMARY OF THE INVENTION

The problem therefore existed of finding compounds of tetravalentvanadium which are easy to prepare, do not decompose at temperatures upto 150° C., have good shelf life, and are soluble in nonpolar organicsolvents.

As a solution to this problem, di(trialkylate)-oxovanates (IV) have beenfound, which correspond to the formula: ##STR2## in which Me representsa metal of the fourth group of the Periodic Table of the Elements and Rrepresents an alkyl moiety of 1 to 20 carbon atoms or an aryl moiety,i.e. aryl of 6-18 carbocyclic carbon atoms.

The new compounds are soluble in nonpolar organic solvents and do notdecompose even at temperatures of 190° C. Their preparation isaccomplished in a simple, known manner by the reaction of vanadylcarboxylates with alcoholates of titanium or zirconium or hafnium.

In the metal alcoholates that can be used as starting products for thepreparation of the new alcoholates, the alcohol moiety can be either analiphatic or cycloaliphatic or an aromatic moiety. The aliphatic moietycan be straight-chained or branched and can contain up to 20 carbonatoms. Particularly contemplated are aliphatic alcohols derived fromaliphatic hydrocarbons, especially saturated hydrocarbons. Thus thealcohols can be alkanols, alkenols and alkynols as well as their cycliccounterparts. The aromatic moieties are mainly the phenyl and the cresylmoieties, although the aryl compound can have up to 18, preferably up to12 moieties. Examples of compounds of this kind are methyl, titanate,ethyl titanate, n-propyl titanate , isobutyl titanate, nonyl titanate,2-ethylhexyl titanate, cetyl titanate, cresyl titanate, methylzirconate, butyl zirconate, oleyl zirconate (IV), and phenyl zirconate(IV).

The preferred alkyl moieties of metallic acid esters are those having 1to 10 carbon atoms.

These metallic acid esters are reacted with vanadyl carboxylates of theformula VO(OOCR')₂ ' wherein R' is an alkyl moiety of 1 to 5 carbonatoms, preferably the methyl moiety. The molar ratio of vanadylcarboxylate to metallic acid ester is preferably 1:1.8 to 2.2. In thereaction, a half ester of the vanadyl compound ##STR3## develops as anintermediate product, although it does not have to be isolated, and alsothe corresponding carboxylic acid ester.

The reaction can be performed in the absence of solvent, although it isrecommendable to perform the reaction in a high-boiling solvent, such astoluene, xylene, cumene, tetrahydronaphthalene (Tetralin),decahydronaphthalene (Decalin) or aliphatic, high-boiling hydrocarbons.The half ester forms at temperatures between 100° and 150° C. Heating iscontinued further until the reaction is complete, the temperatures beingable to be increased up to 200° C.

Generally the compounds of the invention are prepared by performing thereaction at 80° to 240° C., preferably 120° to 200° C. lower pressuresdown to 5 mbar and higher pressures up to 2,5 bar can be used within thegiven temperature ranges.

The carboxylic acid ester that develops in the reaction is continuouslydistilled out during the reaction provided that its boiling point isbelow the boiling point of the solvent used. The progress of thereaction can also be followed by measuring the amount of carboxylic acidester that is distilled out.

After the reaction has ended, any remaining carboxylic acid ester isdistilled out, and the new metallic acid ester obtained is freed ofsolvent and vacuum distilled if necessary.

The new metallic acid esters are soluble in nonpolar organic solventsand can accordingly be used as catalysts in solution. In addition, theyare soluble in lower-boiling aromatic and nonpolar aliphatic solvents,such as for example benzene, hexane or benzine gasoline fractions. Thesesolutions are stable for several months at room temperature if moistureis excluded.

The new compounds are suitable as catalysts in the polymerization ofolefins and dienes and in the copolymerization thereof. Furthermore,they can also be used as catalysts in the polymerization of vinylchloride, acrylic acid esters or epoxides, and in esterification ortransesterification reactions. They can be used in the same manipulativemanner and in the same amounts as known olefin and diene polymerizationcatalyst which contains vanadium. Similarly when employed for vinylpolymerization or polymerization of acrylic acid esters or epoxides, thenew vanadium compounds are employed in the same manner and in the sameamount as conventional catalysts therefor.

The new compounds can be used to form homopolymers, copolymers andterpolymers of the above named monomers.

EXAMPLES Example 1 Preparation of di(tri-butyltitanate)-oxo-vanadate(IV)of the formula O═V--[O--Ti(O--C₄ H₉)₃ ]₂.

6.46 kg of vanadium-oxo-acetate (96.7% pure) was suspended in 30 litersof a mixture of aliphatic hydrocarbons of a boiling range between 184°and 211° C. Then, with stirring, 23 kg of titanium tetrabutylate wasslowly added, and then the mixture was heated. As soon as a temperatureof 155° C. had been reached in the reaction mixture, the acetic acidbutyl ester that formed during the reaction was distilled out through ashort fractionating column. While this ester was being removed theinternal temperature rose to 190° C.

Then the solvent was distilled out in a rotary evaporator at 1 to 10mbar. A brownish-black, viscous liquid is obtained. Analysis shows acontent of 16.3% titanium and 8.6% vanadium.

The new compound is miscible in n-hexane in all proportions. Thesesolvents are stable for more than three months at room temperature, ifmoisture is excluded.

EXAMPLE 2 Preparation of di(triacetyltitanate)-oxo-vanadate(IV)

3.8 kg of vanadyl acetate was dissolved in a high-boiling, aliphatichydrocarbon. 46.6 kg of cetyl titanate was added to this solution. Thefurther processing of this mixture was performed as in Example 1. Afterthe solvent, the ester and a small amount of excess cetyl alcohol hasbeen distilled out, a chocolate-brown, solid product is obtainedcontaining 4% vanadium. It is soluble in Decalin or other hydrocarbons,for example.

EXAMPLE 3

3.8 kg of vanadyl acetate was dissolved in a high-boiling hydrocarbonmixture. After the addition of 54.5 kg of stearyl titanate, the mixturewas heated with refluxing for two hours, then the solvent as well as theexcess stearyl alcohol was distilled out insofar as possible, finally inthe vacuum produced by an oil pump. What remained was a solid,chocolate-brown product which, at a titanium content of 4% and avanadium content of 1.9%, consisted mainly of the desireddi(tristearyltitanate)-oxo-vanadate(IV). It, too, is easily soluble inaliphatic hydrocarbons (n-hexane, for example).

0.533 kg of vanadyl (IV) acetate was suspended in a mixture of aliphatichydrocarbons, having a boiling range between 184 to 211 degree C. Tothis suspension 2,5 kg of zirconium butylate was added. The resultingmixture was heated up to 135 degree C. and then boiled under refluxduring one hour, during this period the vanadyl acetate was dissolvedand butyl acetate was formed. The latter was distilled off, whereby thetemperature of the sump rose to 185 degree C. The resultingblack-greenish solution, containing some solid by-product, was filteredand then the solvent was distilled off at 0,1 mbar by means of a rotaryfilm evaporator. A dark brown product of a tough resenous consistencywas obtained containing 22,9% of zirconium and 7,6% of vanadium.

What is claimed is:
 1. In a process for the formation of a polymer of amonomer of the group consisting of olefins, dienes, styrene, vinylchloride, acrylic acid esters and epoxides, wherein the monomer issubjected to polymerization conditions in the presence of apolymerization catalyst therefor, the improvement wherein saidpolymerization catalyst comprises a compound of tetravalent vanadium ofthe general formula ##STR4## wherein M represents a metal of the fourthgroup of the Periodic Table of the Elements andR represents an alkyl,cycloalkyl or aryl moiety of 1 to 20 carbon atoms.
 2. A processaccording to claim 1, wherein M is titanium.
 3. A process according toclaim 1, wherein the monomer is an olefin.
 4. A process according toclaim 1, wherein said monomer is vinyl chloride.
 5. A process accordingto claim 1, wherein R is alkyl.
 6. A process according to claim 1,wherein the tetravalent vanadium compound isdi(tri-butyltitanate)-oxo-vanadate (IV).
 7. A process according to claim1, wherein said tetravalent vanadium compound isdi(triacetyltitanate)-oxo-vanadate (IV).
 8. A process according to claim1, wherein said tetravalent vanadium compound isdi(tristearyltitanate)-oxo-vanadate (IV).